Variable speed friction gearing



y 4, 1933- .1. H. ROBERTSON ET AL 1,916,533

VARIABLE SPEED FRICTION GEARING I Filed Aug. 20, 1951 Patented July 4, 1933 UNITED STATES PATENT OFFICE JOHN HOGG ROBERTSON AND LEONARD GUTTERIDGE, OF LONDON, ENGLAND VARIABLE SPEED FRICTION GEARING Application filed August 20, 1931, Serial No. 558,266. and in Great Britain September 12, 1930.

This, invention relates to variable speed friction gearing and more particularly to continuously variable friction gearing of the type in which a driven member is adapted 5 to make face contact with a driving member, a direct drive position being provided in which the two members engage coaxially in the manner of a disc or cone clutch, and a series of indirect drive positions being proplaced laterally to a variable" extent so that contact takes place .eccentrically between thethe driven member, for example automatically in accordance with its speed by means of a governor device. i c 1 .In applying a speederesponsive control by a centrifugal governor directly to the axial displacement-of a driving member having a wide range of speed, as inv the case of motor car engines, the pressure set up betweenthe driving and drivenmembers, if sufficient'at the lower speeds of rotation, becomes altogether excessive at the higher speeds, this excessive pressure is objectionable not only as introducing unnecessary loading upon the parts and thrust bearings, but also as making the governor control the dominant factor in determining the gear ratio to the prejudice or exclusion of the other automatic or man-.

ual controls. Moreover the engaging pressure between the members to transmit a sition when rotating athigher speed than in the lower gear positions obtained'whenit is rotating comparatively slowly. v

The present invention has for its object to provide an improved form of governor r 'mechanism, which furnishes the necessary 0 pressure'for the axial displacement in acvided in which the driven member is disthe idling speed, and the gear members 'out of engagement.

low gear position.

given torque in the direct drive position needs According to this invention, the centrifugal mass or masses of the governor mechanism is or are so arranged as to have a limit- 5 ed movement which is completed within a selected increase of speed, and to transmit the movement to the axially displaceable member by means of yielding connections which become fully loaded at the completion of the centrifugalmass movement.

The invention is hereafter described with reference to the accompanying drawing, in which: 7

Figure l is a longitudinal section of the"? driving and driven members of a'variable friction gearing ofthe type mentioned above, the parts being in the position of rest or of Figure 2 is a partial view with the parts i i in the position corresponding to a higher speed and the gear members engaged inthe Figure 3 is a similar view with the parts in the high speed position and the gear mem "bers engaged in the direct drive position.

Figures 4 and 5 are details of two forms of screw and nut connections for producing the compression of the springs controlling the sliding member of the gearing.

Referring to Figures 1 to 3, the invention is shown applied to a governor-controlled driving'memb'er'in the form of a coned disc a slidable axially upon the-exterior of a cy-.. lindrical box or cas ng I) mounted in place of or in addition to the flywheel upon an engine shaft 0 or otherv driving shaft, and adapted to engage adriven member is which is displaceable laterally in relation to the axis of the driving member, for transmitting power to the driven shaftl at variable speed. I

From the rear wall of the casing b there project into the interior a number ofevenly spaced parallel studs (Z on which are pivotally mounted a like number of lever arms a ,carrying at their free ends the governor force; the outward movement of the weights is limited by their engagement with adj ustahis or other stops, for example with the periphery of the casing b. Diametrically opposite to the stud (Z, supporting the lever arm 0, there is shown a control device comprising a spring 8 enclosed in a thimble s screwed into the rear wall of the casing, a rod 8 screwed into the disc a carrying a block 8 upon which the spring presses in order to hold the disc a in the retracted position.

The front ends d of the studsd enter corresponding socket holesa in the back of the slidable cover which forms the c oned driving disc a. Between the pivotal bosses e of the governor arms and theiback of the slidable cover, coiled springs g are mounted around the studs (Z, these springs tending when compressed to push the slidable cover an axially forward from the casing I) against the action of the springs s. The compression of the Springs 9 is produced by the outward partrotary movement of the governor arms under the action of centrifugal force, for example by quick-pitch screw and nut connections,

helicalc'am faces or the like means for con verting rotary movement into longitudinal movement. As shown more clearly in Fig ure l, the bosses (2* of the lever arms may be. formed as nuts engaged upon screw-threaded portion d of the studs; alternatively there may be, employed separate screw-threaded bushes or sleeves engaging the screwed bosses of the lev er arms and slidable without rotation upon the studs.

I Figure 5 illustrates the combination of screw bosses c engaged upon screw-threaded portions (Z of the studs, with screwed bosses 0 upon other lever arms secured beside the first 6, these bosses e engaging screw-threaded bushes or sleeves 71, slidable without rotation upon squared portions (Z of the studs; the two screwed connections are maderight and left hand respectively, so that the bushes k serving to compress the springs 9 have approximately twice the axial movement of the lever bosses e e.

In the construction according to Figures 1 to l, the coiled compression springs g, which constitute the yielding connections for transmitting the limited movement of the levers e 7 produced by the governor weights to the axially displaceableconed disc a, may have their ends fixed to the lever bosses e and to the slidable cover a respectively, so as to control the lever arms a by torsional effect in additionto their compression.

In the position of'rest, or when the casing b is revolving at low speed, the lever armsare retained in their inmost position by the action of the control springs s, or by the torsicnal action of the springs g as mentioned above. The driving disc at therefore remains out of contact with the driven member Zr: of

the gearing, giving a free position (Figure sufficient to transmit the drive substantially.

without slip. As the gear ratio is raised, by lateral displacement of the driven member 70, the axial displacement of the driving member a as it approaches the direct drive position (Figure 3) will correspondingly ,relieve the yielding connections 9 so as'to reduce the engaging pressure between the frictional members a is until in the direct drive posi tion the required minimum pressure is "exerted. So long as the speed remains at or above the value corresponding to the extreme outer position of the levers e, the variation of pressure will depend solely upon the position of the laterally displaceable member is; but if the speed falls below-this value,"then the relief of the yielding connections g due to the partial return movement inwards of and displacements the driven f'rnenflberit" forcing the disc a inwards and reacting upon the yielding connections 9 so as to restore the engaging pressure substantially to that required for transmitting the torqueunder the new conditions. I The springs and weights are so designed and arranged that the full outward-movement of the lever arms is produced at a relatively low speed, for example twice or three times the idling speed of. the engine, the arms or weights being then in engagement with their stops so that no further'increase of the spring pressure upon the slidable disc ble. What we claim is 1. In variable speed frictiongearing comprising a rotarydriving'member having a eccentricity, the combination of a centrifugal governor rotating with said driving member, and yieldlng sprlng means for ex a can occur even at the highest speeds possi erting pressure upon said driving member to 7 cause its axial displacement into engagement with sald driven" member, sald' 'yleldmg spring means compressed by ope'rationuof said centrifugal governor and pI'GSSlHgdirectly against said driving member. I

2. In variable speed friction gearing comprising'a rotary driving'membe'r having a part-conical face, and a driven member adapted to make face contact with said driving member-in positions of varying eccentricity in relation to said'driving member, the combination of a governor lever, avplvotal support for said lever, said support rotating with said driving member, yielding spring means for exerting pressure upon said driving member to cause its axial displacement into engagement with said driven member, and means for compressing said yielding spring means by pivotal movement of said lever, said compressing means including a helical connection for converting rotary movement into longitudinal movement.

8. In variable speed friction gearing comprising a rotary driving member having a part-conical face, and a driven member adapted to make face contact with said driving member in positions of varying eccentricity in relation to said driving member, the combination of a governor lever, a pivotal support for said lever, said support rotating with said driving member, yielding,

means for exerting pressure upon said driving member to cause its axialdisplacement into engagement with said driven member, a screw connection for operating said yielding means by pivotal movement of said lever, and means for returning said lever.

4. In variable speed friction gearing comprising a rotary driving member having a part-conical face, and a driven member adapted to make face contact with said driving member in positions of varying eccentricity in relation to said driving member, the

combination of a governor lever having a screw-threaded boss, a screw-threaded support for said lever, said support rotating I with said driving member, and a compression spring engaged between said screwthreaded boss and said driving member, the rotation of said lever upon said support due to centrifugal action causing said boss to travel along said support, and the longitudinal movement of said boss producing compression ofsaid spring to exert'yielding pressure upon said driving member for its engagement with said driven member.

In testimony whereof we have affixed our signatures. Y

JOHN HOGG ROBERTSON. LEONARD GUTTERIDGE. 

